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Linux/net/sunrpc/xdr.c

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  1 /*
  2  * linux/net/sunrpc/xdr.c
  3  *
  4  * Generic XDR support.
  5  *
  6  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
  7  */
  8 
  9 #include <linux/module.h>
 10 #include <linux/slab.h>
 11 #include <linux/types.h>
 12 #include <linux/string.h>
 13 #include <linux/kernel.h>
 14 #include <linux/pagemap.h>
 15 #include <linux/errno.h>
 16 #include <linux/sunrpc/xdr.h>
 17 #include <linux/sunrpc/msg_prot.h>
 18 
 19 /*
 20  * XDR functions for basic NFS types
 21  */
 22 __be32 *
 23 xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
 24 {
 25         unsigned int    quadlen = XDR_QUADLEN(obj->len);
 26 
 27         p[quadlen] = 0;         /* zero trailing bytes */
 28         *p++ = cpu_to_be32(obj->len);
 29         memcpy(p, obj->data, obj->len);
 30         return p + XDR_QUADLEN(obj->len);
 31 }
 32 EXPORT_SYMBOL_GPL(xdr_encode_netobj);
 33 
 34 __be32 *
 35 xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
 36 {
 37         unsigned int    len;
 38 
 39         if ((len = be32_to_cpu(*p++)) > XDR_MAX_NETOBJ)
 40                 return NULL;
 41         obj->len  = len;
 42         obj->data = (u8 *) p;
 43         return p + XDR_QUADLEN(len);
 44 }
 45 EXPORT_SYMBOL_GPL(xdr_decode_netobj);
 46 
 47 /**
 48  * xdr_encode_opaque_fixed - Encode fixed length opaque data
 49  * @p: pointer to current position in XDR buffer.
 50  * @ptr: pointer to data to encode (or NULL)
 51  * @nbytes: size of data.
 52  *
 53  * Copy the array of data of length nbytes at ptr to the XDR buffer
 54  * at position p, then align to the next 32-bit boundary by padding
 55  * with zero bytes (see RFC1832).
 56  * Note: if ptr is NULL, only the padding is performed.
 57  *
 58  * Returns the updated current XDR buffer position
 59  *
 60  */
 61 __be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
 62 {
 63         if (likely(nbytes != 0)) {
 64                 unsigned int quadlen = XDR_QUADLEN(nbytes);
 65                 unsigned int padding = (quadlen << 2) - nbytes;
 66 
 67                 if (ptr != NULL)
 68                         memcpy(p, ptr, nbytes);
 69                 if (padding != 0)
 70                         memset((char *)p + nbytes, 0, padding);
 71                 p += quadlen;
 72         }
 73         return p;
 74 }
 75 EXPORT_SYMBOL_GPL(xdr_encode_opaque_fixed);
 76 
 77 /**
 78  * xdr_encode_opaque - Encode variable length opaque data
 79  * @p: pointer to current position in XDR buffer.
 80  * @ptr: pointer to data to encode (or NULL)
 81  * @nbytes: size of data.
 82  *
 83  * Returns the updated current XDR buffer position
 84  */
 85 __be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
 86 {
 87         *p++ = cpu_to_be32(nbytes);
 88         return xdr_encode_opaque_fixed(p, ptr, nbytes);
 89 }
 90 EXPORT_SYMBOL_GPL(xdr_encode_opaque);
 91 
 92 __be32 *
 93 xdr_encode_string(__be32 *p, const char *string)
 94 {
 95         return xdr_encode_array(p, string, strlen(string));
 96 }
 97 EXPORT_SYMBOL_GPL(xdr_encode_string);
 98 
 99 __be32 *
100 xdr_decode_string_inplace(__be32 *p, char **sp,
101                           unsigned int *lenp, unsigned int maxlen)
102 {
103         u32 len;
104 
105         len = be32_to_cpu(*p++);
106         if (len > maxlen)
107                 return NULL;
108         *lenp = len;
109         *sp = (char *) p;
110         return p + XDR_QUADLEN(len);
111 }
112 EXPORT_SYMBOL_GPL(xdr_decode_string_inplace);
113 
114 /**
115  * xdr_terminate_string - '\0'-terminate a string residing in an xdr_buf
116  * @buf: XDR buffer where string resides
117  * @len: length of string, in bytes
118  *
119  */
120 void
121 xdr_terminate_string(struct xdr_buf *buf, const u32 len)
122 {
123         char *kaddr;
124 
125         kaddr = kmap_atomic(buf->pages[0]);
126         kaddr[buf->page_base + len] = '\0';
127         kunmap_atomic(kaddr);
128 }
129 EXPORT_SYMBOL_GPL(xdr_terminate_string);
130 
131 void
132 xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
133                  struct page **pages, unsigned int base, unsigned int len)
134 {
135         struct kvec *head = xdr->head;
136         struct kvec *tail = xdr->tail;
137         char *buf = (char *)head->iov_base;
138         unsigned int buflen = head->iov_len;
139 
140         head->iov_len  = offset;
141 
142         xdr->pages = pages;
143         xdr->page_base = base;
144         xdr->page_len = len;
145 
146         tail->iov_base = buf + offset;
147         tail->iov_len = buflen - offset;
148 
149         xdr->buflen += len;
150 }
151 EXPORT_SYMBOL_GPL(xdr_inline_pages);
152 
153 /*
154  * Helper routines for doing 'memmove' like operations on a struct xdr_buf
155  */
156 
157 /**
158  * _shift_data_right_pages
159  * @pages: vector of pages containing both the source and dest memory area.
160  * @pgto_base: page vector address of destination
161  * @pgfrom_base: page vector address of source
162  * @len: number of bytes to copy
163  *
164  * Note: the addresses pgto_base and pgfrom_base are both calculated in
165  *       the same way:
166  *            if a memory area starts at byte 'base' in page 'pages[i]',
167  *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
168  * Also note: pgfrom_base must be < pgto_base, but the memory areas
169  *      they point to may overlap.
170  */
171 static void
172 _shift_data_right_pages(struct page **pages, size_t pgto_base,
173                 size_t pgfrom_base, size_t len)
174 {
175         struct page **pgfrom, **pgto;
176         char *vfrom, *vto;
177         size_t copy;
178 
179         BUG_ON(pgto_base <= pgfrom_base);
180 
181         pgto_base += len;
182         pgfrom_base += len;
183 
184         pgto = pages + (pgto_base >> PAGE_CACHE_SHIFT);
185         pgfrom = pages + (pgfrom_base >> PAGE_CACHE_SHIFT);
186 
187         pgto_base &= ~PAGE_CACHE_MASK;
188         pgfrom_base &= ~PAGE_CACHE_MASK;
189 
190         do {
191                 /* Are any pointers crossing a page boundary? */
192                 if (pgto_base == 0) {
193                         pgto_base = PAGE_CACHE_SIZE;
194                         pgto--;
195                 }
196                 if (pgfrom_base == 0) {
197                         pgfrom_base = PAGE_CACHE_SIZE;
198                         pgfrom--;
199                 }
200 
201                 copy = len;
202                 if (copy > pgto_base)
203                         copy = pgto_base;
204                 if (copy > pgfrom_base)
205                         copy = pgfrom_base;
206                 pgto_base -= copy;
207                 pgfrom_base -= copy;
208 
209                 vto = kmap_atomic(*pgto);
210                 if (*pgto != *pgfrom) {
211                         vfrom = kmap_atomic(*pgfrom);
212                         memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
213                         kunmap_atomic(vfrom);
214                 } else
215                         memmove(vto + pgto_base, vto + pgfrom_base, copy);
216                 flush_dcache_page(*pgto);
217                 kunmap_atomic(vto);
218 
219         } while ((len -= copy) != 0);
220 }
221 
222 /**
223  * _copy_to_pages
224  * @pages: array of pages
225  * @pgbase: page vector address of destination
226  * @p: pointer to source data
227  * @len: length
228  *
229  * Copies data from an arbitrary memory location into an array of pages
230  * The copy is assumed to be non-overlapping.
231  */
232 static void
233 _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
234 {
235         struct page **pgto;
236         char *vto;
237         size_t copy;
238 
239         pgto = pages + (pgbase >> PAGE_CACHE_SHIFT);
240         pgbase &= ~PAGE_CACHE_MASK;
241 
242         for (;;) {
243                 copy = PAGE_CACHE_SIZE - pgbase;
244                 if (copy > len)
245                         copy = len;
246 
247                 vto = kmap_atomic(*pgto);
248                 memcpy(vto + pgbase, p, copy);
249                 kunmap_atomic(vto);
250 
251                 len -= copy;
252                 if (len == 0)
253                         break;
254 
255                 pgbase += copy;
256                 if (pgbase == PAGE_CACHE_SIZE) {
257                         flush_dcache_page(*pgto);
258                         pgbase = 0;
259                         pgto++;
260                 }
261                 p += copy;
262         }
263         flush_dcache_page(*pgto);
264 }
265 
266 /**
267  * _copy_from_pages
268  * @p: pointer to destination
269  * @pages: array of pages
270  * @pgbase: offset of source data
271  * @len: length
272  *
273  * Copies data into an arbitrary memory location from an array of pages
274  * The copy is assumed to be non-overlapping.
275  */
276 void
277 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
278 {
279         struct page **pgfrom;
280         char *vfrom;
281         size_t copy;
282 
283         pgfrom = pages + (pgbase >> PAGE_CACHE_SHIFT);
284         pgbase &= ~PAGE_CACHE_MASK;
285 
286         do {
287                 copy = PAGE_CACHE_SIZE - pgbase;
288                 if (copy > len)
289                         copy = len;
290 
291                 vfrom = kmap_atomic(*pgfrom);
292                 memcpy(p, vfrom + pgbase, copy);
293                 kunmap_atomic(vfrom);
294 
295                 pgbase += copy;
296                 if (pgbase == PAGE_CACHE_SIZE) {
297                         pgbase = 0;
298                         pgfrom++;
299                 }
300                 p += copy;
301 
302         } while ((len -= copy) != 0);
303 }
304 EXPORT_SYMBOL_GPL(_copy_from_pages);
305 
306 /**
307  * xdr_shrink_bufhead
308  * @buf: xdr_buf
309  * @len: bytes to remove from buf->head[0]
310  *
311  * Shrinks XDR buffer's header kvec buf->head[0] by
312  * 'len' bytes. The extra data is not lost, but is instead
313  * moved into the inlined pages and/or the tail.
314  */
315 static void
316 xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
317 {
318         struct kvec *head, *tail;
319         size_t copy, offs;
320         unsigned int pglen = buf->page_len;
321 
322         tail = buf->tail;
323         head = buf->head;
324 
325         WARN_ON_ONCE(len > head->iov_len);
326         if (len > head->iov_len)
327                 len = head->iov_len;
328 
329         /* Shift the tail first */
330         if (tail->iov_len != 0) {
331                 if (tail->iov_len > len) {
332                         copy = tail->iov_len - len;
333                         memmove((char *)tail->iov_base + len,
334                                         tail->iov_base, copy);
335                 }
336                 /* Copy from the inlined pages into the tail */
337                 copy = len;
338                 if (copy > pglen)
339                         copy = pglen;
340                 offs = len - copy;
341                 if (offs >= tail->iov_len)
342                         copy = 0;
343                 else if (copy > tail->iov_len - offs)
344                         copy = tail->iov_len - offs;
345                 if (copy != 0)
346                         _copy_from_pages((char *)tail->iov_base + offs,
347                                         buf->pages,
348                                         buf->page_base + pglen + offs - len,
349                                         copy);
350                 /* Do we also need to copy data from the head into the tail ? */
351                 if (len > pglen) {
352                         offs = copy = len - pglen;
353                         if (copy > tail->iov_len)
354                                 copy = tail->iov_len;
355                         memcpy(tail->iov_base,
356                                         (char *)head->iov_base +
357                                         head->iov_len - offs,
358                                         copy);
359                 }
360         }
361         /* Now handle pages */
362         if (pglen != 0) {
363                 if (pglen > len)
364                         _shift_data_right_pages(buf->pages,
365                                         buf->page_base + len,
366                                         buf->page_base,
367                                         pglen - len);
368                 copy = len;
369                 if (len > pglen)
370                         copy = pglen;
371                 _copy_to_pages(buf->pages, buf->page_base,
372                                 (char *)head->iov_base + head->iov_len - len,
373                                 copy);
374         }
375         head->iov_len -= len;
376         buf->buflen -= len;
377         /* Have we truncated the message? */
378         if (buf->len > buf->buflen)
379                 buf->len = buf->buflen;
380 }
381 
382 /**
383  * xdr_shrink_pagelen
384  * @buf: xdr_buf
385  * @len: bytes to remove from buf->pages
386  *
387  * Shrinks XDR buffer's page array buf->pages by
388  * 'len' bytes. The extra data is not lost, but is instead
389  * moved into the tail.
390  */
391 static void
392 xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
393 {
394         struct kvec *tail;
395         size_t copy;
396         unsigned int pglen = buf->page_len;
397         unsigned int tailbuf_len;
398 
399         tail = buf->tail;
400         BUG_ON (len > pglen);
401 
402         tailbuf_len = buf->buflen - buf->head->iov_len - buf->page_len;
403 
404         /* Shift the tail first */
405         if (tailbuf_len != 0) {
406                 unsigned int free_space = tailbuf_len - tail->iov_len;
407 
408                 if (len < free_space)
409                         free_space = len;
410                 tail->iov_len += free_space;
411 
412                 copy = len;
413                 if (tail->iov_len > len) {
414                         char *p = (char *)tail->iov_base + len;
415                         memmove(p, tail->iov_base, tail->iov_len - len);
416                 } else
417                         copy = tail->iov_len;
418                 /* Copy from the inlined pages into the tail */
419                 _copy_from_pages((char *)tail->iov_base,
420                                 buf->pages, buf->page_base + pglen - len,
421                                 copy);
422         }
423         buf->page_len -= len;
424         buf->buflen -= len;
425         /* Have we truncated the message? */
426         if (buf->len > buf->buflen)
427                 buf->len = buf->buflen;
428 }
429 
430 void
431 xdr_shift_buf(struct xdr_buf *buf, size_t len)
432 {
433         xdr_shrink_bufhead(buf, len);
434 }
435 EXPORT_SYMBOL_GPL(xdr_shift_buf);
436 
437 /**
438  * xdr_stream_pos - Return the current offset from the start of the xdr_stream
439  * @xdr: pointer to struct xdr_stream
440  */
441 unsigned int xdr_stream_pos(const struct xdr_stream *xdr)
442 {
443         return (unsigned int)(XDR_QUADLEN(xdr->buf->len) - xdr->nwords) << 2;
444 }
445 EXPORT_SYMBOL_GPL(xdr_stream_pos);
446 
447 /**
448  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
449  * @xdr: pointer to xdr_stream struct
450  * @buf: pointer to XDR buffer in which to encode data
451  * @p: current pointer inside XDR buffer
452  *
453  * Note: at the moment the RPC client only passes the length of our
454  *       scratch buffer in the xdr_buf's header kvec. Previously this
455  *       meant we needed to call xdr_adjust_iovec() after encoding the
456  *       data. With the new scheme, the xdr_stream manages the details
457  *       of the buffer length, and takes care of adjusting the kvec
458  *       length for us.
459  */
460 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
461 {
462         struct kvec *iov = buf->head;
463         int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
464 
465         BUG_ON(scratch_len < 0);
466         xdr->buf = buf;
467         xdr->iov = iov;
468         xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
469         xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
470         BUG_ON(iov->iov_len > scratch_len);
471 
472         if (p != xdr->p && p != NULL) {
473                 size_t len;
474 
475                 BUG_ON(p < xdr->p || p > xdr->end);
476                 len = (char *)p - (char *)xdr->p;
477                 xdr->p = p;
478                 buf->len += len;
479                 iov->iov_len += len;
480         }
481 }
482 EXPORT_SYMBOL_GPL(xdr_init_encode);
483 
484 /**
485  * xdr_reserve_space - Reserve buffer space for sending
486  * @xdr: pointer to xdr_stream
487  * @nbytes: number of bytes to reserve
488  *
489  * Checks that we have enough buffer space to encode 'nbytes' more
490  * bytes of data. If so, update the total xdr_buf length, and
491  * adjust the length of the current kvec.
492  */
493 __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
494 {
495         __be32 *p = xdr->p;
496         __be32 *q;
497 
498         /* align nbytes on the next 32-bit boundary */
499         nbytes += 3;
500         nbytes &= ~3;
501         q = p + (nbytes >> 2);
502         if (unlikely(q > xdr->end || q < p))
503                 return NULL;
504         xdr->p = q;
505         xdr->iov->iov_len += nbytes;
506         xdr->buf->len += nbytes;
507         return p;
508 }
509 EXPORT_SYMBOL_GPL(xdr_reserve_space);
510 
511 /**
512  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
513  * @xdr: pointer to xdr_stream
514  * @pages: list of pages
515  * @base: offset of first byte
516  * @len: length of data in bytes
517  *
518  */
519 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
520                  unsigned int len)
521 {
522         struct xdr_buf *buf = xdr->buf;
523         struct kvec *iov = buf->tail;
524         buf->pages = pages;
525         buf->page_base = base;
526         buf->page_len = len;
527 
528         iov->iov_base = (char *)xdr->p;
529         iov->iov_len  = 0;
530         xdr->iov = iov;
531 
532         if (len & 3) {
533                 unsigned int pad = 4 - (len & 3);
534 
535                 BUG_ON(xdr->p >= xdr->end);
536                 iov->iov_base = (char *)xdr->p + (len & 3);
537                 iov->iov_len  += pad;
538                 len += pad;
539                 *xdr->p++ = 0;
540         }
541         buf->buflen += len;
542         buf->len += len;
543 }
544 EXPORT_SYMBOL_GPL(xdr_write_pages);
545 
546 static void xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
547                 unsigned int len)
548 {
549         if (len > iov->iov_len)
550                 len = iov->iov_len;
551         xdr->p = (__be32*)iov->iov_base;
552         xdr->end = (__be32*)(iov->iov_base + len);
553         xdr->iov = iov;
554         xdr->page_ptr = NULL;
555 }
556 
557 static int xdr_set_page_base(struct xdr_stream *xdr,
558                 unsigned int base, unsigned int len)
559 {
560         unsigned int pgnr;
561         unsigned int maxlen;
562         unsigned int pgoff;
563         unsigned int pgend;
564         void *kaddr;
565 
566         maxlen = xdr->buf->page_len;
567         if (base >= maxlen)
568                 return -EINVAL;
569         maxlen -= base;
570         if (len > maxlen)
571                 len = maxlen;
572 
573         base += xdr->buf->page_base;
574 
575         pgnr = base >> PAGE_SHIFT;
576         xdr->page_ptr = &xdr->buf->pages[pgnr];
577         kaddr = page_address(*xdr->page_ptr);
578 
579         pgoff = base & ~PAGE_MASK;
580         xdr->p = (__be32*)(kaddr + pgoff);
581 
582         pgend = pgoff + len;
583         if (pgend > PAGE_SIZE)
584                 pgend = PAGE_SIZE;
585         xdr->end = (__be32*)(kaddr + pgend);
586         xdr->iov = NULL;
587         return 0;
588 }
589 
590 static void xdr_set_next_page(struct xdr_stream *xdr)
591 {
592         unsigned int newbase;
593 
594         newbase = (1 + xdr->page_ptr - xdr->buf->pages) << PAGE_SHIFT;
595         newbase -= xdr->buf->page_base;
596 
597         if (xdr_set_page_base(xdr, newbase, PAGE_SIZE) < 0)
598                 xdr_set_iov(xdr, xdr->buf->tail, xdr->buf->len);
599 }
600 
601 static bool xdr_set_next_buffer(struct xdr_stream *xdr)
602 {
603         if (xdr->page_ptr != NULL)
604                 xdr_set_next_page(xdr);
605         else if (xdr->iov == xdr->buf->head) {
606                 if (xdr_set_page_base(xdr, 0, PAGE_SIZE) < 0)
607                         xdr_set_iov(xdr, xdr->buf->tail, xdr->buf->len);
608         }
609         return xdr->p != xdr->end;
610 }
611 
612 /**
613  * xdr_init_decode - Initialize an xdr_stream for decoding data.
614  * @xdr: pointer to xdr_stream struct
615  * @buf: pointer to XDR buffer from which to decode data
616  * @p: current pointer inside XDR buffer
617  */
618 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
619 {
620         xdr->buf = buf;
621         xdr->scratch.iov_base = NULL;
622         xdr->scratch.iov_len = 0;
623         xdr->nwords = XDR_QUADLEN(buf->len);
624         if (buf->head[0].iov_len != 0)
625                 xdr_set_iov(xdr, buf->head, buf->len);
626         else if (buf->page_len != 0)
627                 xdr_set_page_base(xdr, 0, buf->len);
628         if (p != NULL && p > xdr->p && xdr->end >= p) {
629                 xdr->nwords -= p - xdr->p;
630                 xdr->p = p;
631         }
632 }
633 EXPORT_SYMBOL_GPL(xdr_init_decode);
634 
635 /**
636  * xdr_init_decode - Initialize an xdr_stream for decoding data.
637  * @xdr: pointer to xdr_stream struct
638  * @buf: pointer to XDR buffer from which to decode data
639  * @pages: list of pages to decode into
640  * @len: length in bytes of buffer in pages
641  */
642 void xdr_init_decode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
643                            struct page **pages, unsigned int len)
644 {
645         memset(buf, 0, sizeof(*buf));
646         buf->pages =  pages;
647         buf->page_len =  len;
648         buf->buflen =  len;
649         buf->len = len;
650         xdr_init_decode(xdr, buf, NULL);
651 }
652 EXPORT_SYMBOL_GPL(xdr_init_decode_pages);
653 
654 static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
655 {
656         unsigned int nwords = XDR_QUADLEN(nbytes);
657         __be32 *p = xdr->p;
658         __be32 *q = p + nwords;
659 
660         if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))
661                 return NULL;
662         xdr->p = q;
663         xdr->nwords -= nwords;
664         return p;
665 }
666 
667 /**
668  * xdr_set_scratch_buffer - Attach a scratch buffer for decoding data.
669  * @xdr: pointer to xdr_stream struct
670  * @buf: pointer to an empty buffer
671  * @buflen: size of 'buf'
672  *
673  * The scratch buffer is used when decoding from an array of pages.
674  * If an xdr_inline_decode() call spans across page boundaries, then
675  * we copy the data into the scratch buffer in order to allow linear
676  * access.
677  */
678 void xdr_set_scratch_buffer(struct xdr_stream *xdr, void *buf, size_t buflen)
679 {
680         xdr->scratch.iov_base = buf;
681         xdr->scratch.iov_len = buflen;
682 }
683 EXPORT_SYMBOL_GPL(xdr_set_scratch_buffer);
684 
685 static __be32 *xdr_copy_to_scratch(struct xdr_stream *xdr, size_t nbytes)
686 {
687         __be32 *p;
688         void *cpdest = xdr->scratch.iov_base;
689         size_t cplen = (char *)xdr->end - (char *)xdr->p;
690 
691         if (nbytes > xdr->scratch.iov_len)
692                 return NULL;
693         memcpy(cpdest, xdr->p, cplen);
694         cpdest += cplen;
695         nbytes -= cplen;
696         if (!xdr_set_next_buffer(xdr))
697                 return NULL;
698         p = __xdr_inline_decode(xdr, nbytes);
699         if (p == NULL)
700                 return NULL;
701         memcpy(cpdest, p, nbytes);
702         return xdr->scratch.iov_base;
703 }
704 
705 /**
706  * xdr_inline_decode - Retrieve XDR data to decode
707  * @xdr: pointer to xdr_stream struct
708  * @nbytes: number of bytes of data to decode
709  *
710  * Check if the input buffer is long enough to enable us to decode
711  * 'nbytes' more bytes of data starting at the current position.
712  * If so return the current pointer, then update the current
713  * pointer position.
714  */
715 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
716 {
717         __be32 *p;
718 
719         if (nbytes == 0)
720                 return xdr->p;
721         if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
722                 return NULL;
723         p = __xdr_inline_decode(xdr, nbytes);
724         if (p != NULL)
725                 return p;
726         return xdr_copy_to_scratch(xdr, nbytes);
727 }
728 EXPORT_SYMBOL_GPL(xdr_inline_decode);
729 
730 static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len)
731 {
732         struct xdr_buf *buf = xdr->buf;
733         struct kvec *iov;
734         unsigned int nwords = XDR_QUADLEN(len);
735         unsigned int cur = xdr_stream_pos(xdr);
736 
737         if (xdr->nwords == 0)
738                 return 0;
739         /* Realign pages to current pointer position */
740         iov  = buf->head;
741         if (iov->iov_len > cur) {
742                 xdr_shrink_bufhead(buf, iov->iov_len - cur);
743                 xdr->nwords = XDR_QUADLEN(buf->len - cur);
744         }
745 
746         if (nwords > xdr->nwords) {
747                 nwords = xdr->nwords;
748                 len = nwords << 2;
749         }
750         if (buf->page_len <= len)
751                 len = buf->page_len;
752         else if (nwords < xdr->nwords) {
753                 /* Truncate page data and move it into the tail */
754                 xdr_shrink_pagelen(buf, buf->page_len - len);
755                 xdr->nwords = XDR_QUADLEN(buf->len - cur);
756         }
757         return len;
758 }
759 
760 /**
761  * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
762  * @xdr: pointer to xdr_stream struct
763  * @len: number of bytes of page data
764  *
765  * Moves data beyond the current pointer position from the XDR head[] buffer
766  * into the page list. Any data that lies beyond current position + "len"
767  * bytes is moved into the XDR tail[].
768  *
769  * Returns the number of XDR encoded bytes now contained in the pages
770  */
771 unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
772 {
773         struct xdr_buf *buf = xdr->buf;
774         struct kvec *iov;
775         unsigned int nwords;
776         unsigned int end;
777         unsigned int padding;
778 
779         len = xdr_align_pages(xdr, len);
780         if (len == 0)
781                 return 0;
782         nwords = XDR_QUADLEN(len);
783         padding = (nwords << 2) - len;
784         xdr->iov = iov = buf->tail;
785         /* Compute remaining message length.  */
786         end = ((xdr->nwords - nwords) << 2) + padding;
787         if (end > iov->iov_len)
788                 end = iov->iov_len;
789 
790         /*
791          * Position current pointer at beginning of tail, and
792          * set remaining message length.
793          */
794         xdr->p = (__be32 *)((char *)iov->iov_base + padding);
795         xdr->end = (__be32 *)((char *)iov->iov_base + end);
796         xdr->page_ptr = NULL;
797         xdr->nwords = XDR_QUADLEN(end - padding);
798         return len;
799 }
800 EXPORT_SYMBOL_GPL(xdr_read_pages);
801 
802 /**
803  * xdr_enter_page - decode data from the XDR page
804  * @xdr: pointer to xdr_stream struct
805  * @len: number of bytes of page data
806  *
807  * Moves data beyond the current pointer position from the XDR head[] buffer
808  * into the page list. Any data that lies beyond current position + "len"
809  * bytes is moved into the XDR tail[]. The current pointer is then
810  * repositioned at the beginning of the first XDR page.
811  */
812 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
813 {
814         len = xdr_align_pages(xdr, len);
815         /*
816          * Position current pointer at beginning of tail, and
817          * set remaining message length.
818          */
819         if (len != 0)
820                 xdr_set_page_base(xdr, 0, len);
821 }
822 EXPORT_SYMBOL_GPL(xdr_enter_page);
823 
824 static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
825 
826 void
827 xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
828 {
829         buf->head[0] = *iov;
830         buf->tail[0] = empty_iov;
831         buf->page_len = 0;
832         buf->buflen = buf->len = iov->iov_len;
833 }
834 EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
835 
836 /**
837  * xdr_buf_subsegment - set subbuf to a portion of buf
838  * @buf: an xdr buffer
839  * @subbuf: the result buffer
840  * @base: beginning of range in bytes
841  * @len: length of range in bytes
842  *
843  * sets @subbuf to an xdr buffer representing the portion of @buf of
844  * length @len starting at offset @base.
845  *
846  * @buf and @subbuf may be pointers to the same struct xdr_buf.
847  *
848  * Returns -1 if base of length are out of bounds.
849  */
850 int
851 xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
852                         unsigned int base, unsigned int len)
853 {
854         subbuf->buflen = subbuf->len = len;
855         if (base < buf->head[0].iov_len) {
856                 subbuf->head[0].iov_base = buf->head[0].iov_base + base;
857                 subbuf->head[0].iov_len = min_t(unsigned int, len,
858                                                 buf->head[0].iov_len - base);
859                 len -= subbuf->head[0].iov_len;
860                 base = 0;
861         } else {
862                 base -= buf->head[0].iov_len;
863                 subbuf->head[0].iov_len = 0;
864         }
865 
866         if (base < buf->page_len) {
867                 subbuf->page_len = min(buf->page_len - base, len);
868                 base += buf->page_base;
869                 subbuf->page_base = base & ~PAGE_CACHE_MASK;
870                 subbuf->pages = &buf->pages[base >> PAGE_CACHE_SHIFT];
871                 len -= subbuf->page_len;
872                 base = 0;
873         } else {
874                 base -= buf->page_len;
875                 subbuf->page_len = 0;
876         }
877 
878         if (base < buf->tail[0].iov_len) {
879                 subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
880                 subbuf->tail[0].iov_len = min_t(unsigned int, len,
881                                                 buf->tail[0].iov_len - base);
882                 len -= subbuf->tail[0].iov_len;
883                 base = 0;
884         } else {
885                 base -= buf->tail[0].iov_len;
886                 subbuf->tail[0].iov_len = 0;
887         }
888 
889         if (base || len)
890                 return -1;
891         return 0;
892 }
893 EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
894 
895 /**
896  * xdr_buf_trim - lop at most "len" bytes off the end of "buf"
897  * @buf: buf to be trimmed
898  * @len: number of bytes to reduce "buf" by
899  *
900  * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note
901  * that it's possible that we'll trim less than that amount if the xdr_buf is
902  * too small, or if (for instance) it's all in the head and the parser has
903  * already read too far into it.
904  */
905 void xdr_buf_trim(struct xdr_buf *buf, unsigned int len)
906 {
907         size_t cur;
908         unsigned int trim = len;
909 
910         if (buf->tail[0].iov_len) {
911                 cur = min_t(size_t, buf->tail[0].iov_len, trim);
912                 buf->tail[0].iov_len -= cur;
913                 trim -= cur;
914                 if (!trim)
915                         goto fix_len;
916         }
917 
918         if (buf->page_len) {
919                 cur = min_t(unsigned int, buf->page_len, trim);
920                 buf->page_len -= cur;
921                 trim -= cur;
922                 if (!trim)
923                         goto fix_len;
924         }
925 
926         if (buf->head[0].iov_len) {
927                 cur = min_t(size_t, buf->head[0].iov_len, trim);
928                 buf->head[0].iov_len -= cur;
929                 trim -= cur;
930         }
931 fix_len:
932         buf->len -= (len - trim);
933 }
934 EXPORT_SYMBOL_GPL(xdr_buf_trim);
935 
936 static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
937 {
938         unsigned int this_len;
939 
940         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
941         memcpy(obj, subbuf->head[0].iov_base, this_len);
942         len -= this_len;
943         obj += this_len;
944         this_len = min_t(unsigned int, len, subbuf->page_len);
945         if (this_len)
946                 _copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
947         len -= this_len;
948         obj += this_len;
949         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
950         memcpy(obj, subbuf->tail[0].iov_base, this_len);
951 }
952 
953 /* obj is assumed to point to allocated memory of size at least len: */
954 int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
955 {
956         struct xdr_buf subbuf;
957         int status;
958 
959         status = xdr_buf_subsegment(buf, &subbuf, base, len);
960         if (status != 0)
961                 return status;
962         __read_bytes_from_xdr_buf(&subbuf, obj, len);
963         return 0;
964 }
965 EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
966 
967 static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
968 {
969         unsigned int this_len;
970 
971         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
972         memcpy(subbuf->head[0].iov_base, obj, this_len);
973         len -= this_len;
974         obj += this_len;
975         this_len = min_t(unsigned int, len, subbuf->page_len);
976         if (this_len)
977                 _copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
978         len -= this_len;
979         obj += this_len;
980         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
981         memcpy(subbuf->tail[0].iov_base, obj, this_len);
982 }
983 
984 /* obj is assumed to point to allocated memory of size at least len: */
985 int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
986 {
987         struct xdr_buf subbuf;
988         int status;
989 
990         status = xdr_buf_subsegment(buf, &subbuf, base, len);
991         if (status != 0)
992                 return status;
993         __write_bytes_to_xdr_buf(&subbuf, obj, len);
994         return 0;
995 }
996 EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
997 
998 int
999 xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
1000 {
1001         __be32  raw;
1002         int     status;
1003 
1004         status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
1005         if (status)
1006                 return status;
1007         *obj = be32_to_cpu(raw);
1008         return 0;
1009 }
1010 EXPORT_SYMBOL_GPL(xdr_decode_word);
1011 
1012 int
1013 xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
1014 {
1015         __be32  raw = cpu_to_be32(obj);
1016 
1017         return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
1018 }
1019 EXPORT_SYMBOL_GPL(xdr_encode_word);
1020 
1021 /* If the netobj starting offset bytes from the start of xdr_buf is contained
1022  * entirely in the head or the tail, set object to point to it; otherwise
1023  * try to find space for it at the end of the tail, copy it there, and
1024  * set obj to point to it. */
1025 int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
1026 {
1027         struct xdr_buf subbuf;
1028 
1029         if (xdr_decode_word(buf, offset, &obj->len))
1030                 return -EFAULT;
1031         if (xdr_buf_subsegment(buf, &subbuf, offset + 4, obj->len))
1032                 return -EFAULT;
1033 
1034         /* Is the obj contained entirely in the head? */
1035         obj->data = subbuf.head[0].iov_base;
1036         if (subbuf.head[0].iov_len == obj->len)
1037                 return 0;
1038         /* ..or is the obj contained entirely in the tail? */
1039         obj->data = subbuf.tail[0].iov_base;
1040         if (subbuf.tail[0].iov_len == obj->len)
1041                 return 0;
1042 
1043         /* use end of tail as storage for obj:
1044          * (We don't copy to the beginning because then we'd have
1045          * to worry about doing a potentially overlapping copy.
1046          * This assumes the object is at most half the length of the
1047          * tail.) */
1048         if (obj->len > buf->buflen - buf->len)
1049                 return -ENOMEM;
1050         if (buf->tail[0].iov_len != 0)
1051                 obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
1052         else
1053                 obj->data = buf->head[0].iov_base + buf->head[0].iov_len;
1054         __read_bytes_from_xdr_buf(&subbuf, obj->data, obj->len);
1055         return 0;
1056 }
1057 EXPORT_SYMBOL_GPL(xdr_buf_read_netobj);
1058 
1059 /* Returns 0 on success, or else a negative error code. */
1060 static int
1061 xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
1062                  struct xdr_array2_desc *desc, int encode)
1063 {
1064         char *elem = NULL, *c;
1065         unsigned int copied = 0, todo, avail_here;
1066         struct page **ppages = NULL;
1067         int err;
1068 
1069         if (encode) {
1070                 if (xdr_encode_word(buf, base, desc->array_len) != 0)
1071                         return -EINVAL;
1072         } else {
1073                 if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
1074                     desc->array_len > desc->array_maxlen ||
1075                     (unsigned long) base + 4 + desc->array_len *
1076                                     desc->elem_size > buf->len)
1077                         return -EINVAL;
1078         }
1079         base += 4;
1080 
1081         if (!desc->xcode)
1082                 return 0;
1083 
1084         todo = desc->array_len * desc->elem_size;
1085 
1086         /* process head */
1087         if (todo && base < buf->head->iov_len) {
1088                 c = buf->head->iov_base + base;
1089                 avail_here = min_t(unsigned int, todo,
1090                                    buf->head->iov_len - base);
1091                 todo -= avail_here;
1092 
1093                 while (avail_here >= desc->elem_size) {
1094                         err = desc->xcode(desc, c);
1095                         if (err)
1096                                 goto out;
1097                         c += desc->elem_size;
1098                         avail_here -= desc->elem_size;
1099                 }
1100                 if (avail_here) {
1101                         if (!elem) {
1102                                 elem = kmalloc(desc->elem_size, GFP_KERNEL);
1103                                 err = -ENOMEM;
1104                                 if (!elem)
1105                                         goto out;
1106                         }
1107                         if (encode) {
1108                                 err = desc->xcode(desc, elem);
1109                                 if (err)
1110                                         goto out;
1111                                 memcpy(c, elem, avail_here);
1112                         } else
1113                                 memcpy(elem, c, avail_here);
1114                         copied = avail_here;
1115                 }
1116                 base = buf->head->iov_len;  /* align to start of pages */
1117         }
1118 
1119         /* process pages array */
1120         base -= buf->head->iov_len;
1121         if (todo && base < buf->page_len) {
1122                 unsigned int avail_page;
1123 
1124                 avail_here = min(todo, buf->page_len - base);
1125                 todo -= avail_here;
1126 
1127                 base += buf->page_base;
1128                 ppages = buf->pages + (base >> PAGE_CACHE_SHIFT);
1129                 base &= ~PAGE_CACHE_MASK;
1130                 avail_page = min_t(unsigned int, PAGE_CACHE_SIZE - base,
1131                                         avail_here);
1132                 c = kmap(*ppages) + base;
1133 
1134                 while (avail_here) {
1135                         avail_here -= avail_page;
1136                         if (copied || avail_page < desc->elem_size) {
1137                                 unsigned int l = min(avail_page,
1138                                         desc->elem_size - copied);
1139                                 if (!elem) {
1140                                         elem = kmalloc(desc->elem_size,
1141                                                        GFP_KERNEL);
1142                                         err = -ENOMEM;
1143                                         if (!elem)
1144                                                 goto out;
1145                                 }
1146                                 if (encode) {
1147                                         if (!copied) {
1148                                                 err = desc->xcode(desc, elem);
1149                                                 if (err)
1150                                                         goto out;
1151                                         }
1152                                         memcpy(c, elem + copied, l);
1153                                         copied += l;
1154                                         if (copied == desc->elem_size)
1155                                                 copied = 0;
1156                                 } else {
1157                                         memcpy(elem + copied, c, l);
1158                                         copied += l;
1159                                         if (copied == desc->elem_size) {
1160                                                 err = desc->xcode(desc, elem);
1161                                                 if (err)
1162                                                         goto out;
1163                                                 copied = 0;
1164                                         }
1165                                 }
1166                                 avail_page -= l;
1167                                 c += l;
1168                         }
1169                         while (avail_page >= desc->elem_size) {
1170                                 err = desc->xcode(desc, c);
1171                                 if (err)
1172                                         goto out;
1173                                 c += desc->elem_size;
1174                                 avail_page -= desc->elem_size;
1175                         }
1176                         if (avail_page) {
1177                                 unsigned int l = min(avail_page,
1178                                             desc->elem_size - copied);
1179                                 if (!elem) {
1180                                         elem = kmalloc(desc->elem_size,
1181                                                        GFP_KERNEL);
1182                                         err = -ENOMEM;
1183                                         if (!elem)
1184                                                 goto out;
1185                                 }
1186                                 if (encode) {
1187                                         if (!copied) {
1188                                                 err = desc->xcode(desc, elem);
1189                                                 if (err)
1190                                                         goto out;
1191                                         }
1192                                         memcpy(c, elem + copied, l);
1193                                         copied += l;
1194                                         if (copied == desc->elem_size)
1195                                                 copied = 0;
1196                                 } else {
1197                                         memcpy(elem + copied, c, l);
1198                                         copied += l;
1199                                         if (copied == desc->elem_size) {
1200                                                 err = desc->xcode(desc, elem);
1201                                                 if (err)
1202                                                         goto out;
1203                                                 copied = 0;
1204                                         }
1205                                 }
1206                         }
1207                         if (avail_here) {
1208                                 kunmap(*ppages);
1209                                 ppages++;
1210                                 c = kmap(*ppages);
1211                         }
1212 
1213                         avail_page = min(avail_here,
1214                                  (unsigned int) PAGE_CACHE_SIZE);
1215                 }
1216                 base = buf->page_len;  /* align to start of tail */
1217         }
1218 
1219         /* process tail */
1220         base -= buf->page_len;
1221         if (todo) {
1222                 c = buf->tail->iov_base + base;
1223                 if (copied) {
1224                         unsigned int l = desc->elem_size - copied;
1225 
1226                         if (encode)
1227                                 memcpy(c, elem + copied, l);
1228                         else {
1229                                 memcpy(elem + copied, c, l);
1230                                 err = desc->xcode(desc, elem);
1231                                 if (err)
1232                                         goto out;
1233                         }
1234                         todo -= l;
1235                         c += l;
1236                 }
1237                 while (todo) {
1238                         err = desc->xcode(desc, c);
1239                         if (err)
1240                                 goto out;
1241                         c += desc->elem_size;
1242                         todo -= desc->elem_size;
1243                 }
1244         }
1245         err = 0;
1246 
1247 out:
1248         kfree(elem);
1249         if (ppages)
1250                 kunmap(*ppages);
1251         return err;
1252 }
1253 
1254 int
1255 xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1256                   struct xdr_array2_desc *desc)
1257 {
1258         if (base >= buf->len)
1259                 return -EINVAL;
1260 
1261         return xdr_xcode_array2(buf, base, desc, 0);
1262 }
1263 EXPORT_SYMBOL_GPL(xdr_decode_array2);
1264 
1265 int
1266 xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1267                   struct xdr_array2_desc *desc)
1268 {
1269         if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1270             buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1271                 return -EINVAL;
1272 
1273         return xdr_xcode_array2(buf, base, desc, 1);
1274 }
1275 EXPORT_SYMBOL_GPL(xdr_encode_array2);
1276 
1277 int
1278 xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
1279                 int (*actor)(struct scatterlist *, void *), void *data)
1280 {
1281         int i, ret = 0;
1282         unsigned int page_len, thislen, page_offset;
1283         struct scatterlist      sg[1];
1284 
1285         sg_init_table(sg, 1);
1286 
1287         if (offset >= buf->head[0].iov_len) {
1288                 offset -= buf->head[0].iov_len;
1289         } else {
1290                 thislen = buf->head[0].iov_len - offset;
1291                 if (thislen > len)
1292                         thislen = len;
1293                 sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
1294                 ret = actor(sg, data);
1295                 if (ret)
1296                         goto out;
1297                 offset = 0;
1298                 len -= thislen;
1299         }
1300         if (len == 0)
1301                 goto out;
1302 
1303         if (offset >= buf->page_len) {
1304                 offset -= buf->page_len;
1305         } else {
1306                 page_len = buf->page_len - offset;
1307                 if (page_len > len)
1308                         page_len = len;
1309                 len -= page_len;
1310                 page_offset = (offset + buf->page_base) & (PAGE_CACHE_SIZE - 1);
1311                 i = (offset + buf->page_base) >> PAGE_CACHE_SHIFT;
1312                 thislen = PAGE_CACHE_SIZE - page_offset;
1313                 do {
1314                         if (thislen > page_len)
1315                                 thislen = page_len;
1316                         sg_set_page(sg, buf->pages[i], thislen, page_offset);
1317                         ret = actor(sg, data);
1318                         if (ret)
1319                                 goto out;
1320                         page_len -= thislen;
1321                         i++;
1322                         page_offset = 0;
1323                         thislen = PAGE_CACHE_SIZE;
1324                 } while (page_len != 0);
1325                 offset = 0;
1326         }
1327         if (len == 0)
1328                 goto out;
1329         if (offset < buf->tail[0].iov_len) {
1330                 thislen = buf->tail[0].iov_len - offset;
1331                 if (thislen > len)
1332                         thislen = len;
1333                 sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
1334                 ret = actor(sg, data);
1335                 len -= thislen;
1336         }
1337         if (len != 0)
1338                 ret = -EINVAL;
1339 out:
1340         return ret;
1341 }
1342 EXPORT_SYMBOL_GPL(xdr_process_buf);
1343 
1344 

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